What are typical applications for Double Check Valve Assemblies? May be used where the degree of hazard is low, meaning that the non-potable source is polluted rather than contaminated.


What factors can cause a backpressure backflow condition? Backpressure backflow is created whenever the downstream pressure exceeds the supply pressure which is possible in installations such as heating systems, elevated tanks, and pressure-producing systems.


What is backflow? Defined by the United States Environmental Protection Agency as "the flow of water or other liquids, mixtures, or substances into the distribution pipes of a potable supply of water from any source or sources other than its intended source".


What is backpressure? A condition when the fire protection system pressure is higher than the drinking water supply, pushing the fire protection system water back into the drinking water supply. This situation can be caused by fire protection system thermal expansion, high rise building elevated pressures.


What is backsiphonage? Backsiphonage can be created when there is stoppage of the water supply due to nearby fire-fighting, repairs or breaks in city main, etc.


Where is a Double Check Valve Assembly used? It may be used as protection of all direct connections through which foreign material might enter the potable system in concentration which would constitute a nuisance or aesthetically objectionable, such as air, steam, food, or other material which does not constitute a health hazard.


Why is there concern over the contamination of safe drinking water by connection to a fire protection system? Water from a fireline system can backflow into the drinking water system. Fire protection systems are most commonly constructed of uncoated black iron pipe which is considered by plumbing officials to be unacceptable as water system piping material.